This invention relates generally to new and improved apparatus, and components thereof, for removing cores of thermoplastic and elastomeric material.
Surgical aspiration is a well established medical technique for clearing operative sites of biological fluids and tissue, enabling the surgeon to obtain a clear view of the procedure. An enhancement to surgical aspiration, known as ultrasonic surgical aspiration, has been developed within the last twenty years to make possible direct aspiration of soft tissues, without the need for separate dissecting instruments, in surgical procedures. This art is principally described by Banko (U.S. Pat. No. 3,589,363) and Wuchinich (U.S. Pat. Nos. 4,063,557; 4,223,676; 4,425,115; 4,493,694; 4,516,398; 4,750,902; 4,750,488).
More recently, the use of ultrasonic vibration to cut and remove methylmethacrylate bone cement has been described by Englebrecht (U.S. Pat. No. 4,248,232) and Klapper (U.S. Pat. No. 5,019,083). The inventor of the present invention extended the technique to actual simultaneous removal and aspiration of the removed bone cement, e.g. methylmethacrylate, a thermoplastic material. The extensions of this technique are disclosed in U.S. patent application Ser. No. 07/529,029, entitled "APPARATUS AND METHOD FOR REMOVAL OF CEMENT FROM BONE CAVITIES," filed May 25, 1990 and U.S. patent application Ser. No. 07/439,114, entitled "ENDOSCOPIC ULTRASONIC ROTARY ELECTROCAUTERIZING ASPIRATOR," filed Nov. 17, 1989; the first figure of these applications is FIG. 1 of the present drawings. More particularly, it will be understood that the present invention is an improvement of the apparatus shown in FIG. 1.
Referring to FIG. 1, a femur 1 is shown following removal of the prosthetic implant 3. A cavity 4 remains whose walls are lined with bone cement 2. This bone cement is excavated or removed by the ultrasonic apparatus 30 having a hollow ultrasonic tip 6 that vibrates in the directions indicated by arrow 15. The tip 6 is a tubular tip of acoustically conductive material mounted to and aligned with a longitudinally extending tubular ultrasonic conductor 18 of acoustically conductive material which conductor is mounted to the handpiece 17. Surrounding and acoustically coupled to the conductor 18 is an ultrasonic transducer 19 connected to an ultrasonic generator 21 by the transducer power cable 12. The rearward end of the conductor 18 is connected to a vacuum receptacle or canister 14 by flexible tubing 11 which tubing may be provided with an optional trap 13 of suitable porous or mesh material. The canister 14 may be connected to a suitable vacuum source 23 by other flexible tubing 24. In operation, the tubular tip 6 is vibrated at a suitable ultrasonic frequency and is applied to the rim of bone cement 2 and this application locally melts the bone cement 2 of the thermoplastic material which material is then drawn or aspirated into the tubular tip 6 by the suction applied to the rear end of the conductor 18 and applied through the conductor to the tubular tip 6. The melted cement recrystallizes within the tubular tip 6 into a solid sliver or core of bone cement or thermoplastic material and it will be understood that it is within this context that the expression "cores of material (e.g. thermoplastic material) are removed and inserted into the tip (or tube)" is used in this specification and in the appended claims. Then the core is drawn or aspirated through the connector 18, tubing 11 and into the canister or receptacle 14, or if present into the optional trap 13, by the suction from the source 23. This operation is repeated, and as it is repeated successive cores of removed bone cement are drawn or aspirated into either the trap 13 or receptacle 14 by the suction applied to the rear end of the conductor 18. The pathway of a removed cylindrical cores of recrystallized bone cement is illustrated by the cores identified by numerical designation 26 and shown in solid outline in FIG. 1. Typically, the canister or receptacle 14 is located on the floor of the operating room, and to provide the surgeon operating the handpiece 17 of the ultrasonic apparatus 30 with the maneuverability required for the removal of the bone cement 2 as described above, the flexible tubing 11 must be several feet in length. During maneuvering of the handpiece 17 of the ultrasonic apparatus 30, curvature is imparted to the flexible tubing 11, and since the removed cores of bone cement 26 are linear the possibility exists that the aspirated cores of bone cement 26 may lodge in such curvature and progressively develop into an obstruction or blockage in the tubing 11 as successive removed cores jam against one another in the curvature of the tubing. Without special provision for immediate, in-line collection of the removed cylindrical cores of bone cement, the acoustical surgical procedure of removing the bone cement 2, for example in hip joint revision arthoplasty, is or can be confounded by repeated loss of suction or aspiration and inordinate amounts of time spent clearing or freeing the suction passage through the tubing 11 from a blockage of removed bone cement cores 26. Such a blockage removal causes an interruption of the bone cement removal procedure which causes the patient to be on the life support system a longer amount of time than is desirable; it is generally believed that the longer the patient is on a life support system the greater the opportunity for an embolism to develop. Thus, the inherent safety and speediness of ultrasonic bone cement removal can be severely compromised by the extended amount of time taken to perform the surgical procedure, such as the noted hip joint revision arthoplasty, without the provision of apparatus which receives and collects the removed cylindrical cores of bone cement 26 in a manner which prevents the cores of removed bone cement from being jammed together in the suction or aspiration passageway, particularly flexible tubing such as tubing 11 of FIG. 1, thereby enabling uninterrupted and hence relatively quick use of the ultrasonic apparatus 30 by the surgeon in performing the required removal of the bone cement 2. Accordingly, there exists a need in this art for the provision of such bone cement receiving and collection apparatus.